import java.util.Scanner;

public class JavaMethod {
    public static void main(String[] args) {
        //判断素数
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int i=2;
        for ( i = 2; i < n/2; i++) {
            if(n%i==0){
                System.out.println("no");
                break;
            }
        }
        if(i==n){
            System.out.println("是素数");
        }
    }
   
  






    public static void main3(String[] args) {
        //根据年龄，打印出当前年龄的人是少年（18以下），青年（19—28），中年（29-55），老年（56以上）
        Scanner scanner = new Scanner(System.in);
        int age = scanner.nextInt();
        if(age < 18){
            System.out.println("少年");
        }
        else if(age<28){
            System.out.println("青年");
        }
        else if (age<55) {
            System.out.println("中年");
        }
        else{
            System.out.println("老年");
        }
    }




    public static void main1(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        for (int i = 31; i >= 1; i-=2) {
            System.out.print(((n>>i)&1)+ " ");
        }
        System.out.println();
        for (int i = 30; i >= 0; i-=2) {
            System.out.print(((n>>i)&1)+ " ");
        }
        System.out.println();

    }


    public static void main2(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        while(n != 0){

            System.out.println(n%10);
            n /= 10;
        }
    }
}



/*
    int i=1;
    int count=0;
    Scanner scanner = new Scanner(System.in);

        while(i<=3){
                String n = scanner.next();
                if(n=="1234567"){
                System.out.println("密码正确");
                }
                else{
                System.out.println("密码错误，请重新输入");
                i++;
                }
                }*/
